Power consumption is a critical design constraint in many electronic devices. This is especially true of mobile devices that are usually operated using supplied DC power. Such electronic devices often contain integrated circuits that process information digitally and consume appreciable amounts of power during operation. Most dynamic power consumption in portable electronic devices such as video players occurs when their digital circuitry is actively switching, such as when decoding compressed video data to display motion video to interconnected displays.
Numerous formats suitable for organizing digital data for easy storage and convenient playback exist. In particular, digital video may be distributed using storage formats such as those used in the popular DVD format or newer, higher resolution formats such as Blu-ray. They may alternatively be streamed over a data network. Compressed video formats employed in DVDs, which are still widely available, store video in standard definition (SD) resolution. However, the newer formats which are becoming increasingly popular and are being incorporated into current and the next generation of consumer electronic devices, encode video in high definition (HD) resolution.
For example, Blu-ray supports a high definition primary video stream, a secondary video stream, two independent HD graphics streams, several audio tracks, and a background stream. These streams are used to provide improved menu interfaces, subtitles and other features that enhance user experience.
However, the improved quality and feature set listed above necessitate encoding substantial additional digital data onto a Blu-ray disc (BD). Decoding BD content would therefore require extra decoding and processing steps by decoder hardware in order to display the encoded HD video and audio content, and to provide additional features and improvements. Unfortunately, this would entail increased power consumption by the decoder hardware during playback.
Conventional power reduction techniques often emphasize optimizations at the physical circuit level, such as using lower frequency clock signal inputs, shutting down portions of a digital circuit, or reducing the supply voltage, in order to conserve power. Such techniques therefore treat many types of circuits including video decoders, generic microprocessors, memory controllers and others in essentially the same fashion and although each circuit may be geared towards different purposes.
Conventional techniques may thus fail to deliver adequate power reduction since they do not take particular application contexts into account. Accordingly, there is a need for improved power conservation techniques suitable for digital audio/video devices such as BD players.